1. Field of the Invention
This invention relates to an axial piston machine utilizing a swashplate design. A cylinder drum is mounted so that it can rotate around an axis of rotation. The cylinder drum is provided with cylinder bores, in each of which a piston is mounted so that it can be displaced longitudinally. The pistons are each supported by a sliding shoe on a swashplate. The sliding shoes are in a functional connection by a retaining device, in particular a retaining plate, that rotates synchronously with the cylinder drum.
2. Technical Considerations
On axial piston machines of this general type that are in the form of swashplate machines, the pistons are each supported on the swashplate by a sliding shoe. A sliding shoe ball-and-socket joint is located between the piston and the sliding shoe. When the swashplate machine is in operation, on account of the centrifugal forces acting on the sliding shoe, a tipping moment occurs on the sliding shoes which causes a tipping of the sliding shoes from the swashplate. By means of the retaining device, the sliding shoes are pressed toward the swashplate to prevent a lifting or tipping of the sliding shoes as a result of the tipping moment.
The retaining device can be in the form of a non-positive retaining device, whereby a spring device is provided which pushes the retaining device (and thus the sliding shoe) toward the swashplate. To prevent a tipping of the sliding shoes on account of the centrifugal forces that occur during operation, the spring force of the spring device must be designed for the maximum speed of rotation. However, that requires high spring forces which, during operation at lower speeds of rotation, generate high application forces of the sliding shoes against the swashplate and of the cylinder drum against the control surface. The result is the generation of high friction forces which adversely affect the efficiency of the swashplate machine. In addition, the high application forces lead to increased wear of the swashplate machine.
The retaining device can also be realized in the form of a positive or interlocking retaining device fastened on the housing in the axial direction. On account of the play that is present in the positive or interlocking connection of the retaining device with the housing, the sliding shoes can tip away from the swashplate on account of the centrifugal force that occurs during operation. As a result of which, leaks occur which can reduce the efficiency of the swashplate machine.
An axial piston machine of the general type described above in the form of a swashplate machine is described in DE 10 2005 047 981 A1, herein incorporated by reference.
Therefore, it is an object of the invention to provide a hydrostatic axial piston machine of the general type described above but which has improved efficiency.